'Sunday, Bloody Sunday' was inspired by the killing of 13 innocent people at the hands of the British army in Derry on Sunday January 30, 1972 - a fourteenth person died several months later.

Writing in Rolling Stone in 2010, Bono said of Bloody Sunday in Derry: "It was a day that caused the conflict between the two communities in Northern Ireland - Catholic nationalist and Protestant unionist - to spiral into another dimension: every Irish person conscious on that day has a mental picture of Edward Daly, later the bishop of Derry, holding a blood-stained handkerchief aloft as he valiantly tended to the wounded and the dying."

U2 released their 14th studio album 'Songs of Experience' earlier this month.